The present invention, relating generally to an agricultural baler for forming cylindrical bales of crop material, commonly referred to as a round baler, is directed to an improved tailgate latching apparatus. More particularly, this invention is concerned with an improvement to the latching apparatus that secures the tailgate of a round baler to the main frame during bale formation.
For many years agricultural balers have been used to consolidate and package crop material so as to facilitate the storage and handling of the crop material for later use. Usually, a mower-conditioner cuts and conditions the crop material for windrow drying in the sun. When the cut crop material is properly dried, a baler is pulled along the windrows to pick up the crop material and form it into conveniently sized and shaped round bales. More specifically, the windrow pickup of the baler gathers the cut and windrowed crop material and lifts it into the baling chamber. In a round baler, the baling chamber consists of a pair of opposing sidewalls with a series of belts that rotate and compress the crop material into a cylindrical shape. When the bale has achieved a desired size and density, the operator wraps the bale to ensure that the bale maintains its shape and density. The operator then raises the tailgate of the baler and ejects the bale onto the ground. The tailgate is then closed and the cycle repeated as necessary and desired to manage the field of cut crop material. The utilization of rolls in combination with belts is shown by way of example in the round baler of U.S. Pat. No. 4,870,812, by Richard E. Jennings, et al., which is incorporated in its entirety herein by reference.
It is common practice to use a latching assembly to maintain a round baler tailgate in the closed position during bale formation in the chamber. Prior art latching mechanisms experienced, under certain crop conditions excessive stress on the tailgate pivot pins when the hydraulic cylinder, employed to hold the latch in place during operation, exerts a force on the latch pin. This stress is applied as a rotational force on the tailgate pivot pins. Concurrently, a lateral force is incumbent on the tailgate during bale formation as the package of crop material expands within the chamber. Thus, the latch pin, which is being forced downwardly, transmits a downward force to the entire tailgate, which in turn produces the deleterious rotational force mentioned above, while at the same time a lateral force is being applied to the pivot pins, all of which could cause stress and ultimate fatigue if left uncorrected.
An improved latching mechanism designed to alleviate these stress conditions is shown in U.S. Pat. No. 5,598,690, by John R. McClure et al. which is incorporated in its entirety herein by reference. The baler has a latching assembly for holding the tailgate in the closed position, which assembly comprises a latch arm mounted on the main frame, a latch pin mounted on the tailgate in operative relationship with the latch arm, and means for coupling the lift means to the latch arm for moving the latch arm between latched and unlatched positions corresponding to the open and closed positions of the tailgate. The McClure invention also incorporated a unique means mounted on the main frame for engaging the latch arm to prevent the latch arm from exerting downward force on the tailgate via the latch pin to avoid any resulting transmittal of such downward force to the tailgate hinge shaft.
Due to extensive tolerance buildup in the manufacture of round balers, the relative position of elements of the latching mechanisms of the tailgate latches may vary significantly from one baler to the next and even from side to side on the same baler. The resulting misalignment may easily exceed the alignment variation capability of the known latching mechanisms and thereby prevent the tailgate from being securely latched in a closed position for baling, prevent the tailgate from opening to discharge a completed bale, or result in excessive stresses on tailgate components. Correcting the misalignment is typically performed by grinding portions of the latching mechanism to obtain the proper fit or re-mounting tailgate latch pins to correct the misalignment. Such actions require significant effort. Furthermore, if misalignment in the tailgate latching mechanism occurs as a result of wear in the baler, correcting the problem generally means that the baler must be removed from operation, a correction that is rarely convenient to perform.
It would be a great advantage to provide an easily adjustable tailgate latch for a round baler that overcomes the above-identified problems and disadvantages.